Gastrointestinal transit time (GITT) and segmental colonic transit times were studied in 56 healthy subjects by repeated daily ingestion of 10 radiopaque markers followed by abdominal x-ray. A seven-day procedure including marker intake for 6 days and a single radiograph on day 7 was found to be a simple method to differentiate between rapid, normal and prolonged transit. Addition of 20 distinguishable markers on day 6 helped to describe transit profiles. Healthy women had longer GITT than men (median 2.4 and 1.9 days, respectively) measured as mean 50% excretion time for the ingested doses of markers. For comparisons with patients percentiles for transit were calculated. In constipated patients the 7-day method demonstrated prolonged GITT as well as transit dysfunction in separate colonic segments. The method seems convenient for clinical use in diagnostic as well as therapeutic studies of colonic transit.